High-Current Half-Bridge Motor Driver: Implementing the Infineon BTS7960B
The control of high-current DC motors, particularly in automotive and industrial automation applications, demands robust and efficient driver circuitry. A half-bridge configuration is a fundamental building block for such tasks, enabling bidirectional control (forward/brake/reverse) for DC motors. The Infineon BTS7960B is a highly integrated, high-current half-bridge driver that simplifies this implementation, offering a powerful solution for driving loads up to 43A continuously.
This driver IC combines two key components into a single package: a p-channel high-side MOSFET and an n-channel low-side MOSFET, forming one half of a typical H-bridge. This integration is a significant advantage, as it reduces external component count and board space. The BTS7960B is designed to be used in pairs to form a complete H-bridge for bidirectional DC motor control. Its architecture is built around a charge pump for the high-side switch, which allows for 100% duty cycle operation—a critical feature for delivering maximum power to a motor without interruption.
Key Features and Advantages
The BTS7960B stands out due to its impressive specifications and protective features. Its low on-state resistance (RDS(on)) of typically 16 mΩ (for both FETs combined) is a primary factor in its high efficiency. Low resistance translates to reduced heat generation under high load, allowing for more compact thermal management solutions.
A major strength of this IC is its comprehensive suite of integrated protection functions. These include:
Over-current Protection (IS): Shuts down the driver if the current exceeds a safe threshold.
Over-temperature Protection (TSD): Disables the chip if the junction temperature becomes critical.
Over-voltage Protection (VS): Guards against voltage spikes on the supply line.
Under-voltage Lockout (UVLO): Prevents operation when the supply voltage is too low, ensuring proper switching behavior.
Diagnostic capabilities are provided through the Status Flag (SF) and Inverse Status Flag (INH) pins, which can be monitored by a microcontroller to detect fault conditions like overtemperature or overcurrent, enabling smarter system control.
Implementation and Circuit Design
Implementing a complete H-bridge requires two BTS7960B modules. One module controls one direction of current flow (e.g., forward), while the second controls the opposite direction (e.g., reverse). The control interface is straightforward, typically requiring two microcontroller GPIO pins per BTS7960B module: one for Pulse-Width Modulation (PWM) input to control speed and one for Enable (INH) to enable or disable the output.
Critical design considerations for a successful implementation include:
1. Power Supply Decoupling: Placing large electrolytic capacitors (e.g., 100µF) near the power supply pins and small ceramic capacitors (e.g., 100nF) very close to the IC's VS pin are essential to suppress voltage spikes and provide stable switching.
2. Heatsinking: Due to the high currents involved, a proper PCB heatsink using large copper pours connected to the exposed pad (tab) is mandatory. For continuous high-current operation, an external aluminum heatsink is often required.
3. Current Sensing: While the IC has a diagnostic current sense (IS) pin, it is not designed for precise torque control. For accurate current feedback, an external shunt resistor and amplifier circuit are recommended.
4. Freewheeling Diodes: The module incorporates internal body diodes across the MOSFETs, which handle the inductive kickback from the motor coil during switching. This eliminates the need for external diodes.
By carefully addressing the PCB layout for minimal parasitic inductance and ensuring adequate cooling, designers can leverage the full power of the BTS7960B to create compact, reliable, and high-performance motor drives for demanding applications like electric power steering, industrial actuators, and heavy-duty robotics.
The Infineon BTS7960B is an exceptional choice for engineers seeking a robust, feature-rich, and highly integrated solution for high-current DC motor control. Its combination of high current handling, comprehensive protection features, and simple control interface makes it a superior alternative to discrete MOSFET designs, significantly accelerating development time and improving system reliability.
Keywords:
1. Half-Bridge Driver
2. High-Current
3. BTS7960B
4. Integrated Protection
5. PWM Control
